A perpetuity is a type of a bond that promises to pay a fixed payment periodically (e.g., every six months) but never matures. The payment is defined as a percent of a fixed, stated par. For example, a 5% perpetuity with annual payments and par of $100 is a promise by the issuer to pay the holder 5% of $100, or $5, each year. This payment is called the coupon.

Consider a Venetian prestiti with par value of 10,000 ducats, a coupon rate of 3.9%, and annual coupons. Marco Polo buys one prestiti when price is 60 as a percent of par.

What is the market interest rate at the time of purchase?

Express your answer in percent to two decimal places. Do not type the % symbol. For example, if you calculate a rate of 19.57%, then type 19.57.